This project will continue studies with a unique staphylocidal lipid first detected in staphylococcal abscesses. Attempts will be made to determine the cell type producing the precursor for the cidal lipid and the mechanism whereby the cidal lipid is generated. Studies will be conducted to determine whether differences in extracellular accumulations (capsules, or slime), cell wall, or the membrane account for normal differences in strain sensitivity to the lipids, and whether alteration in these structures can lead to resistance. The production of cidal lipid during the course of lesion evolution in various host species will be measured using a biologic assay previously developed. The nature and distribution of an inhibitor for the cidal lipid will also be explored. Attempts will be made to prepare an antibody to delta toxin and to use this antibody to measure toxin production in vivo. If delta toxin is produced in staphylococcal lesions, it will be determined whether the amounts produced are sufficient to afford the organism protection from the cidal lipid.